This article is part of the Top 10 Unanswered Questions in MPMI invited review series.

That plants recruit beneficial microbes while simultaneously restricting pathogens is critical to their survival. Plants must exclude pathogens; however, most land plants are able to form mutualistic symbioses with arbuscular mycorrhizal fungi. Plants also associate with the complex microbial communities that form the microbiome. The outcome of each symbiotic interaction—whether a specific microbe is pathogenic, commensal, or mutualistic—relies on the specific interplay of host and microbial genetics and the environment. Here, we discuss how plants use metabolites as a gate to select which microbes can be symbiotic. Once present, we discuss how plants integrate multiple inputs to initiate programs of immunity or mutualistic symbiosis and how this paradigm may be expanded to the microbiome. Finally, we discuss how environmental signals are integrated with immunity to fine-tune a thermostat that determines whether a plant engages in mutualism, resistance to pathogens, and shapes associations with the microbiome. Collectively, we propose that the plant immune thermostat is set to select for and tolerate a largely nonharmful microbiome while receptor-mediated decision making allows plants to detect and dynamically respond to the presence of potential pathogens or mutualists.

Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

本文是 MPMI 特邀评论系列中十大未回答问题的一部分。

植物在招募有益微生物的同时限制病原体对它们的生存至关重要。植物必须排除病原体；然而，大多数陆生植物能够与丛枝菌根真菌形成互惠共生。植物还与形成微生物组的复杂微生物群落相关联。每种共生相互作用的结果——无论特定微生物是致病的、共生的还是共生的——取决于宿主和微生物遗传学和环境的特定相互作用。在这里，我们讨论植物如何使用代谢物作为选择哪些微生物可以共生的门。一旦出现，我们将讨论植物如何整合多种输入以启动免疫或共生共生程序，以及如何将这种范式扩展到微生物组。最后，我们讨论了环境信号如何与免疫结合以微调恒温器，该恒温器决定植物是否参与共生、对病原体的抵抗以及与微生物组的关联。总的来说，我们建议将植物免疫恒温器设置为选择和容忍很大程度上无害的微生物组，而受体介导的决策允许植物检测潜在病原体或共生者的存在并对其进行动态响应。

版权所有 © 2021 作者。这是在 CC BY-NC-ND 4.0 国际许可下分发的开放获取文章。